From owner-freebsd-questions@FreeBSD.ORG Fri Dec 30 12:42:25 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 8E488106564A for ; Fri, 30 Dec 2011 12:42:25 +0000 (UTC) (envelope-from rsmith@xs4all.nl) Received: from smtp-vbr7.xs4all.nl (smtp-vbr7.xs4all.nl [194.109.24.27]) by mx1.freebsd.org (Postfix) with ESMTP id 302008FC15 for ; Fri, 30 Dec 2011 12:42:24 +0000 (UTC) Received: from slackbox.erewhon.net (slackbox.xs4all.nl [213.84.242.160]) by smtp-vbr7.xs4all.nl (8.13.8/8.13.8) with ESMTP id pBUCfrul012277; Fri, 30 Dec 2011 13:41:53 +0100 (CET) (envelope-from rsmith@xs4all.nl) Received: by slackbox.erewhon.net (Postfix, from userid 1001) id 365BEBACF; Fri, 30 Dec 2011 13:41:53 +0100 (CET) Date: Fri, 30 Dec 2011 13:41:53 +0100 From: Roland Smith To: UFS User Message-ID: <20111230124153.GA18989@slackbox.erewhon.net> References: <1325229204.34713.YahooMailNeo@web140405.mail.bf1.yahoo.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="cWoXeonUoKmBZSoM" Content-Disposition: inline In-Reply-To: <1325229204.34713.YahooMailNeo@web140405.mail.bf1.yahoo.com> X-GPG-Fingerprint: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 X-GPG-Key: http://www.xs4all.nl/~rsmith/pubkey.txt X-GPG-Notice: If this message is not signed, don't assume I sent it! User-Agent: Mutt/1.5.21 (2010-09-15) X-Virus-Scanned: by XS4ALL Virus Scanner Cc: "freebsd-questions@freebsd.org" Subject: Re: Why do I feel like compact flash is more reliable than SSD ? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Dec 2011 12:42:25 -0000 --cWoXeonUoKmBZSoM Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Dec 29, 2011 at 11:13:24PM -0800, UFS User wrote: > I have run a lot of different FreeBSD systems off (fileservers, firewalls, > routers, etc.) off of compact flash cards[1] and have never had a CF part > fail. >=20 > Most of these were read-only mode, but some of them were left mounted 'rw' > for years (with no swapping, of course). =A0The bottom line is, they never > failed, and some were (and are) in the field for over 8 years now. >=20 > But everyone I know (including me) has had an SSD fail, usually with no > explanation. It seems that unlike disk drives, SMART doesn't really give you a warning w= ith SSDs. But as a counterpoint, who hasn't ever had a harddrive fail? And there might be some negativity bias [http://en.wikipedia.org/wiki/Negativity_bias] at w= ork here too. > So is this just chance, or ... are CF cards really a lot more reliable th= an > SSD ? Although I've been looking at SSD's, I've held off for now because of cost = and small disk sizes. But concrete data is relatively scarce, probably due to t= he fact that SSD's haven't been available _that_ long. There are several studies available for harddisks, e.g. from google [http://labs.google.com/papers/disk_failures.pdf] and Carnagie Mellon [http= ://www.usenix.org/events/fast07/tech/schroeder/schroeder_html/index.html]. Generally, more disks fail as they age. But studies concerning SSD's seem to be almost nonexistant. The most intere= sting inventarization I found was on Tom's Hardware [http://www.tomshardware.com/reviews/ssd-reliability-failure-rate,2923.html= ]. Some interesting quotes covering the main points; Even though our data set is one-twentieth the size of previous studies on hard drives, our information starts to suggest that SLC-based SSDs are no = more reliable than SAS and SATA hard drives. ... Our data center survey exclusively covers Intel SSD failure rates because those are the drives that big businesses currently trust the most. ... Should you be deterred from adopting a solid-state solution? So long as you protect your data through regular backups, which is imperative regardl= ess of your preferred storage technology, then we don't see any reason to shy = away from SSDs. Currently SSD's are too small for my taste. But when that changes, I'll seriously consider switching to an SSD with an equal sized HDD for nightly backups. Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --cWoXeonUoKmBZSoM Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iEYEARECAAYFAk79sZEACgkQEnfvsMMhpyVfCgCfdANJ2GISus4KWP95CaD1MsLM RsUAn02GtbJNXOcfQfdIQ61SEEA6PiZy =/gMa -----END PGP SIGNATURE----- --cWoXeonUoKmBZSoM--